Abstract Tunnel linings are critical components of underground infrastructure but are prone to cracking under complex, nonuniform loads. This study develops a nonlinear dual-parameter bond-based peridynamic (DB–PD) model to simulate crack initiation and propagation in concrete tunnel linings subjected to bias pressure, vault voids, pre-existing cracks, and varying lining thicknesses. The proposed model incorporates normal and tangential bond deformations, enabling accurate representation of the deformation and fracture behavior of concrete linings under tensile–shear and compressive–shear loading. The model is verified through tensile and four-point bending benchmarks and validated against a scaled bias-loading experiment. Numerical results reproduce the experimentally observed crack patterns and load–displacement responses. Parametric analyses reveal that bias angle, defect geometry, and lining thickness significantly influence failure mode and crack distribution.
Systems of building construction. Including fireproof construction, concrete construction
Iffat Jahan Chowdhury, Ayan Saha, Fahim Shahriyar Aditto
et al.
Abstract Self-healing concrete is a cement-based substance that can mend itself from a hairline crack. This experiment examines the effectiveness of the gram-positive cell bacteria Bacillus cereus on the self-healing characteristics of steel-slag bio-concrete (SSBC). The study's ultimate goal is to discern the best proportions of bacteria to incorporate into bio-concrete by examining the fresh, hardened, and self-healing qualities, as well as machine learning (ML) approaches with SHAP and PDP analysis to forecast crack width. As a result, five distinct mix designs were developed by substituting steel slag for varying percentages of sand, e.g., 0%, 10%, 20%, 30%, and 40%. The behavior of steel-slag concrete (SSC) was evaluated through fresh, mechanical, and non-destructive tests (NDT) to determine the optimal percentage of steel slag. After finding the ideal percentage of steel slag, three different bacterial solutions of 12.5 × 105 CFU/ml, 25 × 105 CFU/ml, and 31.25 × 105 CFU/ml were mixed with calcium lactate as a feeder to make SSBC. The compressive strength of the mix, which consisted of 12.5 × 105 CFU/ml, 25 × 105 CFU/ml, and 31.25 × 105 CFU/ml B. cereus bacteria, along with a constant 30% steel slag, increased by 13.85%, 21.75%, and 31.57% at 28 days. In the NDT test, the assessment of the rebound hammer and ultrasonic pulse velocity (UPV) showed a similar tendency to the compressive strength test. Visual observation and scanning electron microscopy (SEM) were done to examine the crack-healing tendency of the SSBC. SEM images revealed that adding B. cereus improved the physical characteristics of the concrete by forming CaCO3 crystals, which heal the microcracks. The CatBoost model exhibits greater precision and reliability, even though the regression coefficient (R2) of the random forest (RF) and artificial neural networks (ANN) models is similarly outstanding.
Systems of building construction. Including fireproof construction, concrete construction
Abstract With the increasing global consumption of coffee, a substantial amount of spent coffee grounds (SCG) is generated. To address this, research has focused on recycling SCG as a renewable fuel, including the production of SCG pellets. When used as fuel in biomass-fired power plants, SCG pellets generate SCG ash, which necessitates effective utilization strategies. This study evaluates the potential of SCG ash as a supplementary cementitious material (SCM) by investigating its effects on concrete properties. SCG ash was produced by drying SCG at 110 °C and combusting it at 900 °C. Concrete specimens were prepared by replacing ordinary Portland cement (OPC) with SCG ash at 5%, 10%, and 15% substitution levels. Fly ash (FA) and blast furnace slag (BFS) were also incorporated to analyze hydration kinetics. X-ray diffraction (XRD) and thermogravimetric analyses confirmed the presence of calcite in SCG ash specimens, while mercury intrusion porosimetry indicated increased porosity with higher SCG ash content. Isothermal calorimetry revealed reduced hydration heat with increasing SCG ash replacement. Notably, concrete containing 5% SCG ash exhibited mechanical properties and durability comparable to plain concrete. Based on these findings, 5% was determined to be the optimal SCG ash substitution level. This study suggests that incorporating SCG ash into concrete can reduce CO₂ emissions from cement production while providing a sustainable recycling method for SCG ash.
Systems of building construction. Including fireproof construction, concrete construction
Dalia Alaa Aldeen Abdulmajed, Sultan A. Daud, Fahed Alrshoudi
Abstract This study investigates the long-term structural behaviour of reinforced concrete beams incorporating recycled aggregates using advanced finite element analysis. Diana FEA software was employed to develop numerical models calibrated against experimental data from two published investigations, incorporating the FIB Model Code 2010 constitutive framework to represent recycled aggregate concrete characteristics. The computational methodology replicated experimental protocols including loading configurations, environmental conditions, and material properties. Following validation, the models demonstrated excellent predictive capability for long-term deflection behaviour, crack propagation, and creep recovery mechanisms. A parametric analysis examined the influence of concrete strength (30–70 MPa), reinforcement ratios, sustained loading, and environmental conditions. Significant findings emerged regarding time-dependent performance. Specimens exhibited a 31% reduction in deflection ratio after 90 days of sustained loading and 23% creep recovery within 10 days of load removal when concrete strength increased from 30 to 70 MPa. Elastic recovery remained independent of reinforcement ratio, whilst higher reinforcement ratios reduced creep recovery capacity. Traditional experimental approaches for predicting long-term structural behaviour are often time-consuming and resource-intensive, limiting their practical application in design processes. These findings provide crucial insights into recycled aggregate concrete beam performance, supporting sustainable construction implementation. The validated numerical framework offers a robust and efficient tool for predicting service-life behaviour of environmentally conscious structural elements, significantly reducing the time and cost associated with conventional experimental prediction methods whilst maintaining accuracy and reliability.
Systems of building construction. Including fireproof construction, concrete construction
Lilia V. Shcherbatykh, Aleksey A. Novikov, Viktor V. Ermak
There is carried out a comparative analysis of the actual problems of organizing the daily activities of the State System for the Prevention and Elimination of Emergency Situations (RSChS) and Civil Defense (GO). The study identified systemic shortcomings in four key areas: planning, management and coordination, preparedness of forces and resources, and public outreach. In the area of planning, the findings indicate a perfunctory nature of planning documents, their untimely updating, and insufficient coordination between different management levels. In the field of management, problems of episodic interdepartmental interaction and imperfections in information technology support were identified. The analysis of the preparedness of forces and resources revealed a gap between theoretical training and practical skills, as well as an unsatisfactory state of equipment and material reserves. Regarding public outreach, the inefficiency of traditional training methods and the insufficient reliability of public warning systems persist. To address the identified issues, a comprehensive approach is proposed, which includes improving the regulatory framework, implementing modern technologies, and revising the training system.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This study proposes a novel method for damage assessment in reinforced concrete beams using bonded piezoelectric transducers (PZTs). By analyzing the transmission and reception of high-frequency waves through PZT pairs attached near lap splices in tensile reinforcement, a wavelet packet-based damage index (DIE) was developed. Four reinforced concrete beams with varying lap splice lengths were subjected to cyclic loading, and the electrical signals from PZT sensors were analyzed. A significant reduction in signal amplitude (33–56%) was observed in lapped splices compared to continuous bars, indicating the discontinuities in the splice regions. The proposed DIE showed strong sensitivity in detecting internal damage before surface cracks became visible. In beams with insufficient lap splice lengths, the DIE values reached above 98% of the maximum damage threshold when 57% and 53% of breaking load were reached, confirming its high sensitivity to brittle splitting behavior. In contrast, beams with sufficient lap lengths showed a gradual increase in DIE values, reaching final damage levels of over 98% when 83% and 78% of the breaking load were attained, respectively, corresponding to ductile flexural failure.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This paper presents the outcomes of a study in which continuous steel fibers, recovered from scrap tires of vehicles, were used to prepare alkali-activated slag-based slurry infiltrated fibrous concrete (SIFCON). In this experimental study, the steel fibers used were 250 mm long, with varying fiber contents of 0%, 1%, 2%, 3%, 4%, and 5%. The alkali-activated SIFCONs were produced by activating ground granulated blast furnace slag (GGBS) with a mixture of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions. Mixtures with ordinary Portland cement (OPC) were also cast for comparison purposes. The feasibility of utilizing finely ground waste glass as a silicate source for chemical activator solution in alkali-activated SIFCONs was also investigated. In this context, two different molar concentrations of NaOH, namely 8 M and 14 M, were employed during production. As activators, one series of mixtures utilized sodium hydroxide and sodium silicate solutions, while the other series replaced sodium silicate with finely ground waste glass. As a result, three different waste materials were utilized in concrete. 30 different mixtures were cast and examined in the experimental study. Load–deflection curves were obtained in three-point bending test and mechanical properties of the mixtures such as compressive, splitting and flexural strengths, fracture energy, and toughness were determined. The flexural strength and toughness increased with the use of waste steel fibers. The continuous waste fibers derived from discarded tires yielded results comparable to commercially available fibers, demonstrating their effectiveness in enhancing mechanical properties. Depending on mix design, the alkali-activated SIFCON attained flexural strength exceeding 75 MPa and compressive strength surpassing 100 MPa. These results suggest that concretes incorporating a variety of waste materials can be effectively combined. This innovative approach bridges an existing gap in the literature by combining alkali activation, waste glass, and waste steel fibers, ultimately yielding a sustainable composite that outperforms normal concretes in terms of mechanical properties while promoting environmental sustainability. Test results demonstrate that it is possible to obtain concrete with comparable mechanical properties while primarily composed of by-products and waste materials. This approach marks a substantial step in achieving high-performance concrete that relies solely on waste or by-products. Graphical Abstract
Systems of building construction. Including fireproof construction, concrete construction
Abstract This paper presents a nonlinear analysis procedure for evaluating the seismic performance of reinforced concrete (RC) bridge columns with lap splices using a novel plastic hinge element considering shear deformation. To accurately assess the inelastic behavior of RC bridge columns, reliable three-dimensional (3D) constitutive models are required. However, developing a 3D nonlinear material model is difficult and computationally intensive. In this study, to address these issues, a new plastic hinge element considering shear deformation for RC bridge columns is developed. The new plastic hinge element is based on the Timoshenko beam theory and utilizes two-noded zero length element with six degrees of freedom. The finite element model was implemented in a computer program named Reinforced Concrete Analysis in Higher Evaluation System Technology (RCAHEST) developed by the authors. The developed plastic hinge element for seismic performance assessment of RC bridge columns with lap splices was validated through comparison of the numerical and experimental results.
Systems of building construction. Including fireproof construction, concrete construction
Zhamilya Mamesh, Dilnura Sailauova, Dichuan Zhang
et al.
Abstract Previous studies have revealed that the contribution of slab reinforcement to the T-beam flexural strength in negative moment regions are not negligible for the seismic capacity design. An effective slab width (i.e., effective width of flanged section) has been proposed, within which the slab reinforcement needs to be included in the calculation of the beam nominal flexural strength in negative moment regions. These studies mainly focused on the cases using normal-strength steel in moment resisting frames. However, recently high-strength steel has been widely used in reinforced concrete moment resisting frames in high seismic regions to avoid congestion near beam-column joints. The use of high-strength steel may affect the beam stiffness due to the fact that it will require less amount of reinforcement, and result in a different normal stress distribution compared to the case with normal-strength steel. Therefore, this paper investigates the slab reinforcement contribution to the flexural strength of the reinforced concrete T-beam designed with high-strength steel in negative moment regions at exterior beam-column joints, for which nonlinear pushover analyses were conducted. Beam reinforcement grade was considered as a primary parameter with several other design variables including slab thickness, height, and span length of the beam. Analytical results show that the use of high-strength steel can result in a wider effective slab width than the case of normal-strength steel for calculating the beam nominal flexural strength under the negative moment. Based on these results, new design equations were proposed.
Systems of building construction. Including fireproof construction, concrete construction
Andrey Yu. Lagozin, Gennady T. Zemsky, Alexander V. Ilyichev
et al.
At the present time the determination of the functional fire hazard class of the objects of protection is carried out at the discretion of users intuitively without the possibility of expert verification, due to the absence of a rule for assigning buildings, structures and fire compartments to functional fire hazard classes. The selection of means and methods of fire protection depends on the correct definition of the functional fire hazard class.
The purpose of the paper is to expand the list of objects belonging to each functional fire hazard class using data from the classifier of capital construction objects, as well as to develop proposals for improving the classification of functional fire hazard.
Systems of building construction. Including fireproof construction, concrete construction
Kourosh Shirani, Mohammad Reisi, Mohammad Safari Savadkoohi
Abstract Besides preventing valuable natural resources from going to waste, using stone waste from stone processing plants in concrete helps reduce environmental pollution and, therefore, offers a convenient route to sustainable development. The present study aims to use granite waste (GW) in high-strength refractory concrete. Sixteen high-strength refractory concrete mixes, including two water-to-binder ratios (W/B = 0.17 and 0.2), two silica-fume-to-binder ratios (SF/B = 0.15 and 0.2), two binder contents (B = 1200 and 1400 kg/m3), and two replacement ratios of silica sand by granite waste (GW/Agg = 0 and 50%) were designed and prepared with high-alumina cement (HAC). The concrete specimens were exposed to 1200 °C. Compressive and flexural strength and scanning electron microscopy (SEM) tests were performed on specimens of concrete mixes before and after heating. It was found that in specimens with high binder content (1400 kg/m3), replacing 50% silica sand with GW (GW/Agg = 50%) in refractory concrete improves compressive and flexural strengths by 3–15 and 4–24% before heating, respectively. It was also shown that using GW to replace silica aggregates in concrete specimens with a 1200 kg/m3 binder content not only did not undermine, but also improved the compressive and flexural strengths of refractory concrete after heating by 20–78% and 15–60%, respectively, as a result of sintering. Meanwhile, in the case of the concrete with 1400 kg/m3 binder content, adding GW exacerbated its loss of compressive and flexural strengths after heating due to little or lack of sintering.
Systems of building construction. Including fireproof construction, concrete construction
Ivan V. Nesterov, Evgeniy V. Pavlov , Vladimir I. Kozlov
et al.
The article discusses the formation of robotics in EMERCOM of Russia as well as the use of robotic facilities (complexes) for elimination of the consequences of natural and anthropogenic emergencies during extinguishing large and complex fires.
The authors present an analysis of scientific institutions’ activities over the past 15 years in the field of development of regulatory documents, as well as construction of robotic facilities (complexes) of various classes for responding units of EMERCOM of Russia.
Systems of building construction. Including fireproof construction, concrete construction
Abstract The effectiveness of seismic retrofitting using three different fibers—carbon fiber (CF), glass fiber (GF), polyethylene terephthalate (PET) fiber—and a fiber combination of aramid fiber (AF) and PET fiber (called hybrid fiber reinforced polymer (HF)) wrapped on reinforced concrete (RC) circular columns was experimentally evaluated. A total of 11 RC circular columns were tested: three control columns and eight retrofitted columns in three different test groups. The purpose of fiber wrapping was flexural strength improvement as well as enhancement of rotational capacity in the plastic hinge region. Mechanical properties of CF, GF, AF, and PET were first defined; that is, CF, GF, and AF exhibited linear stress–strain behavior with limited ultimate strain capacity typically less than 3%, while ductile PET exhibited as much as 15% strain and non-linear stress–strain behavior with a very low elastic modulus. In the RC column tests, all three different fibers and the AF + PET fiber combination were effective in enhancing the strength and ductility but resulted in different structural behaviors and failure modes depending on the fiber type and the fiber amount used. The column sections were then analytically studied by section analysis using the behavior of confined concrete, the non-linear relationship of fiber-reinforced polymer (FRP), and the actual material properties of reinforcement. The analytical and experimental results revealed that ductile PET is beneficial, as it demonstrates more ductile behavior with a degree of strength enhancement similar to that of CF and GF.
Systems of building construction. Including fireproof construction, concrete construction
Abstract Engineered cementitious composites (ECC) show the distinguished characteristics of high post-cracking resistance and ductility. High-strength stainless steel wire rope (HSSSWR) has been successfully used for restoring or strengthening of existing structures. By combining the advantages of these two materials, a new composite system formed by embedding HSSSWR into ECC was proposed and expected to be a promising engineering material for repair or strengthening of structures. To investigate the tensile failure mechanism and mechanical properties of HSSSWR-reinforced ECC, an experimental study on 27 HSSSWR-reinforced ECC plates was conducted considering the effects of the reinforcement ratio of longitudinal HSSSWRs, formula of ECC and width of the plate. Test results revealed that HSSSWR-reinforced ECC exhibit superior post-cracking resistance, deformation capacity and crack-width control capacity. Increasing the reinforcement ratio of longitudinal HSSSWRs can effectively enhance the tensile strength, crack-width control capacity, deformation capacity and tensile toughness of HSSSWR-reinforced ECC. Adding thickener in ECC can significantly improve the crack-width control capacity and deformation capacity of HSSSWR-reinforced ECC due to enhancing uniform distribution of polyvinyl alcohol fibers, but would slightly reduce the cracking stress and maximum tensile stress by bringing small bubbles in the matrix. The tensile properties of HSSSWR-reinforced ECC plates are almost not affected by varying the plate width. Besides, a tensile constitutive model was developed for charactering the stress–strain relationship of HSSSWR-reinforced ECC in tension. Based on mechanical theories and failure characteristics of HSSSWR-reinforced ECC, the model parameters were determined, and calculation equations of cracking stress and tensile strength were proposed. The accuracy of the developed model and calculation equations was verified by test results.
Systems of building construction. Including fireproof construction, concrete construction